This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Objective: To define the ability of rhesus embryonic stem cells to differentiate into trophblasts. We previously found that the differentiation potential of rhesus embryonic stem cell (ESC)-like lines to form trophoblast cells was variable, with this differentiation potential ranging from nondetectable to consistent. We have evaluated the undifferentiated cells by microarray, and identified significant differences with high biological relevance. Outgrowths in a 2-dimensional culture paradigm from rhesus ESC which give morphological evidence of trophoblast formation also express placental MHC class I surface molecules. Microarray analysis of 2-D outgrowths will be compared with freshly obtained trophoblasts from rhesus placentas, and trophoblasts that have been terminally differentiated in culture. These studies will reveal the niche that ESC-derived trophoblasts occupy in normal in vivo placental development. This research used WNPRC Stem Cell Resources. PUBLICATION: Douglas, G.C., C.A. VandeVoort, P. Kumar, T.C. Chang, and T.G. Golos, 2009. Trophoblast stem cells: Models for Investigating Trophectoderm Differentiation and Placental Development. Endocrine Reviews. 30:228-40.